🚀 go-pugleaf

Hair has very nearly been pulled out today..so any help most appreciated.
I also apologize in advance if this problem has been covered elsewhere.

Image ready
Working with a background image (screen grab jpeg) with an overlay of gifs that are tweened between one another for a scrolling animation.

When i click optimize/look at 2-up view, i am given the completed animation, however the background colour has changed from white to pale blue, as opposed to remaining the screen grab image..minus any pale blue!

- Should i import background image as a gif?
- What is actually occurring?
- Have i inadvertently changed a setting?
- How does one stop this happening!!

As before sorry for any repetition, sorry also if this a real dunce question! Must try harder.

Help is most appreciated.